Split an Array, similar to String#split

array_split.rb

class Array
  def split(*separator, include_separator: false)
    if separator.empty?
      if !block_given?
        return enum_for(__method__) if separator.empty? && !block_given?
      end
    elsif block_given?
      raise ArgumentError, "Must either pass a block or a separator, not both"
    else
      separator = separator.first
    end

    current = []
    result  = []

    if block_given?
      each do |item|
        if yield(item)
          result << current
          result << [item] if include_separator
          current = []
        else
          current << item
        end
      end
    else
      each do |item|
        if separator == item
          result << current
          result << [item] if include_separator
          current = []
        else
          current << item
        end
      end
    end
    result << current unless current.empty?

    result
  end
end

if __FILE__ == $0
  require 'test/unit'

  class ArraySplitTest < Test::Unit::TestCase
    def test_all
      assert_equal([[1], [2], [3]], [1,nil,2,nil,3].split(nil))
      assert_equal([[1], [2, 3], [3]], [1,nil,2,3,nil,3].split(nil))
      assert_equal([[1, 2], [4, 5], [7, 8], [10]], [*1..10].split { |e| e % 3 == 0 })
      assert_equal([], [].split { |e| e % 3 == 0 })
      assert_equal([[1], [nil], [2], [nil], [3]], [1,nil,2,nil,3].split(nil, include_separator: true))
    end
  end
end